Ophthalmic lenses have been used for providing an individual with improved visual acuity or visual and/or cosmetic benefits. Recently, it has been proposed that ophthalmic lenses can provide other benefits. For example, ophthalmic lenses can be used as ocular sensors for non-invasive or minimally invasive monitoring of glucose, as disclosed by March in PCT International Publication WO 01/13783. Such ocular sensors for glucose can be used to conveniently, non-invasively and frequently monitor blood glucose levels by determining glucose levels in an ocular fluid, such as tears, aqueous humor, or interstitial fluid, based on the correlation between the blood glucose concentration and the ocular glucose concentration, and whereby to achieve the tight control of blood glucose levels by managing food intake and the dosage and timing of insulin injection. Ocular glucose sensors disclosed by March in PCT International Publication WO 01/13783 can be one potentially useful non-invasive technology.
In order to fully explore the full potential of the ocular glucose sensing technology, there is an issue needed to be addressed. The issue is the out-diffusion of guest materials, such as the fluorescently labeled glucose receptor and/or the fluorescently labeled glucose competitor, from ophthalmic lenses. Such out diffusion may affect the precision and reproducibility of the ocular glucose sensing technology. Therefore, there is a need for a method of forming on an ophthalmic lenses a diffusion-controllable coating capable of controlling out-diffusion or out-flow of guest materials from the ophthalmic lens.
Furthermore, ophthalmic lenses may be served as a device for controlled delivery of therapeutic agents, besides vision corrections. For example, contact lenses may be used as a carrier for drugs to treat eye diseases, e.g., dry eye syndrome. Therefore, there is also a need for a method for forming on an ophthalmic lenses a diffusion-controllable coating capable of controlling release of drugs (guest materials) for treating eye diseases.
In addition, the manufacturing of ophthalmic lenses comprises a lengthy and costly extraction process where unpolymerized materials, such as monomers and macromers in the polymerizable composition for making ophthalmic lenses, are extracted from lenses. It is preferable that such extraction process can be eliminated from the manufacturing of ophthalmic lenses. Therefore, there is a further need for a diffusion-controllable coating capable of preventing unpolymerized raw materials (guest materials) from leaching out of the core of ophthalmic lenses.
One object of this invention is to solve the above problems by using a layer-by-layer coating process to form a diffusion-controllable coating on the surface of medical device, preferably ophthalmic lenses, more preferably contact lenses. Such coating may prevent guest materials from leaching out of the core of ophthalmic lenses or control release of therapeutic agents associated with or entrapped in the medical devices into the eye.
Another object of this invention is to produce medical devices, preferably ophthalmic lenses, more preferably contact lenses, having a diffusion-controllable coating which may prevent guest materials from leaching out of the core of ophthalmic lenses or control release of therapeutic agents associated with or entrapped in the medical devices into the eye.